It has already been known that certain derivatives of 1,4-dihydropyridine-3,5-dicarboxylic acid have pharmacological effects such as vasodilative effects. A variety derivatives of 1,4-dihydropyridine-3,5-dicarboxylic acid have heretofore been synthesized, pharmacological effects of which have also been studied. For example, nifedipine [Vater, W. et al, Arzneim. Forsch., 22, 1(1972)] and nicardipine [Takenaka, T. et al, Arzneim. Forsch., 26, 2172(1976)] have already been put as pharmaceutical products on the market.
These conventional derivatives of 1,4-dihydropyridine-3,5-dicarboxylic acid are however not fully satisfactory. There is thus an outstanding demand for the development of derivatives having still better pharmacological effects.